The theory of adaptation, now known as Lamarckism, claimed that physiological changes of an animal would be transmitted to its offspring. This idea was earlier conjectured in the writings of Hippocrates and Aristotle. Lamarckism, informed by fossil evidence, had more scientific backing than the opinions of ancient philosophers. The usual example of Lamarckism is the long neck of the giraffe.

"The giraffe, by its lofty stature, much elongated neck, fore legs, head and tongue, has its whole frame beautifully adapted for browsing on the higher branches of trees. It can thus obtain food beyond the reach of the other Ungulata or hoofed animals inhabiting the same country; and this must be a great advantage to it during dearths... So under nature with the nascent giraffe, the individuals which were the highest browsers and were able during dearths to reach even an inch or two above the others, will often have been preserved... those individuals which had some one part or several parts of their bodies rather more elongated than usual, would generally have survived. These will have intercrossed and left offspring, either inheriting the same bodily peculiarities, or with a tendency to vary again in the same manner; while the individuals less favoured in the same respects will have been the most liable to perish."[2]

Such a form of natural selection is far slower than selection directly involving sexual attributes, one example of which is the peacock's feathers. This idea is such common knowledge that the Star Trek Ferengi were shown to have evolved large ears, since they are erogenous zones. In the category of "size matters," behavioral studies of giraffes show that the male giraffes with the longest necks are the ones who mate and pass their genes to future generations since they are used in fighting for dominance in a behavior called "necking." The reason for neck lengthening may arise from both the foraging and necking behaviors.

"It's interesting to note that that the lengthening was not consistent... First, only the front portion of the C3 vertebra lengthened in one group of species. The second stage was the elongation of the back portion of the C3 neck vertebra. The modern giraffe is the only species that underwent both stages, which is why it has a remarkably long neck."[4]

Left image, the fossil third cervical vertebrae (C3) of a Samotherium, an extinct giraffe species extant about 7 million years ago. Right image, the third cervical vertebrae of the modern giraffe. The Samotherium exhibits the first stage of elongation, while the modern giraffe shows both the first and second stages responsible for its elongated neck.(Left image and right image by Nikos Solounias of the New York Institute of Technology.)

Solounias and coauthor, Melinda Danowitz, studied 71 fossils of nine extinct and two living species in the giraffe family. This was a major undertaking, since these fossils, collected from the late 19th century and early 20th century, were housed at museums in such places as Austria, England, Germany, Greece, Kenya, and Sweden.[4] They made many measurements of the vertebrae and organized the data in a computer model that tracked the evolutionary elongation.[4]

It was found that there was a stretching of the cranial end of the vertebrae about seven million years ago in the extinct species, Samotherium, which is closely related to the modern giraffe. There was a second elongation only a million years ago at the caudal portion (back-facing) of the vertebrae. As a consequence of these two elongations, the C3 vertebra of the modern giraffe is nine times longer than its width, so it's more than a foot long.[4]

As shown in the figure above, there was both neck lengthening and shortening in the evolution from a Prodremotherium common ancestor, about 25 million years ago. The only extant member of the short neck side of the giraffe family is the okapi.[4] Now that they've researched the giraffe neck, the team intends to study the evolution of the giraffe's long leg bones.[4]